Use language learning apps. Duolingo is a popular one. It has structured lessons that gradually increase in difficulty. But don't rely solely on apps. Read books in the new language, start with children's books as they are easier and gradually move on to more complex literature.
Start with the basics like learning the alphabet and simple greetings. For example, if you're learning Spanish, learn 'hola' which means hello. Then, practice listening to native speakers, like through podcasts or short videos.